Horton

Re: Logical Replication of sequences

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: shveta malik <shveta.malik@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Nisha Moond <nisha.moond412@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Shlok Kyal <shlok.kyal.oss@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Euler Taveira <euler@eulerto.com>, Michael Paquier <michael@paquier.xyz>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, "Jonathan S. Katz" <jkatz@postgresql.org>
Date: 2025-09-01T05:39:31Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Doc: Add documentation for sequence synchronization.

  2. Remove unused assignment in CREATE PUBLICATION grammar.

  3. Add seq_sync_error_count to subscription statistics.

  4. Fix few issues in commit 5509055d69.

  5. Add sequence synchronization for logical replication.

  6. Add worker type argument to logical replication worker functions.

  7. Introduce "REFRESH SEQUENCES" for subscriptions.

  8. Refactor logical worker synchronization code into a separate file.

  9. Standardize use of REFRESH PUBLICATION in code and messages.

  10. Add "ALL SEQUENCES" support to publications.

  11. Expose sequence page LSN via pg_get_sequence_data.

  12. Resume conflict-relevant data retention automatically.

  13. Post-commit review fixes for 228c370868.

  14. Generate GUC tables from .dat file

Attachments

On Tue, 26 Aug 2025 at 11:21, shveta malik <shveta.malik@gmail.com> wrote:
>
> On Thu, Aug 21, 2025 at 10:08 PM vignesh C <vignesh21@gmail.com> wrote:
> >
>
> > I have also addressed all the comments from [1] in the attached
> > v20250823 version patch.
> > [1] - https://www.postgresql.org/message-id/CAA4eK1%2BoVQW8oP%3DLo1X8qac6dzg-fgGQ6R_F_psfokUEqe%2Ba6w%40mail.gmail.com
> >
>
> Thank You for the patches. I see a race condition between alter-seq and refresh.
>
> Say we have triggered REFRESH on sub, and when seq-sync worker is in
> copy_sequences() where it has retrieved the local sequence using
> seqname while it has not locked the sequence-relation yet, if
> meanwhile we alter sequence and change its name, seq-sync worker ends
> up syncing that renamed sequence values with old-fetched sequence.
> Steps:
>
> 1) create a sequence seq0 on pub and sub
> 2) do REFRESH PUBLICATION SEQ on sub
> 3) In seq-sync worker, during copy_sequences() hold debugger at:
> seqinfo->remote_seq_fetched = true;
> 4) rename sequence on sub :  ALTER SEQUENCE seq0 RENAME TO seq1;
> 5) release debugger in seq-sync worker. It will end up syncing seq1
> using seq0 fetched from pub.

Thanks for reporting this, this is handled in the attached version of patch.

Regards,
Vignesh